Snowmobile suspension systems generally include a pair of aluminum slide rails, which support the endless drive track and provide a structure to which the lower ends of the hydraulic shock absorbers are attached. The bottom surface of the slide rail which is in sliding contact with the track is covered with a hard plastic slide strip, generally made of Ultra High Molecular Weight Polyethylene (UHMWPE), to reduce the friction between the drive track and the slide rails. These aluminum slide rails also act as a guide which keeps the endless track in-line such that the drive sprockets are continuously in-line with driving holes in the track.
Steel clips are typically located on the inside surface of the endless track between each consecutive driving hole, each clip having a flat portion which slides under the slide rail and an upwardly extending portion which aligns with the inner edge of the slide rail. These steel clips therefore keep the drive track aligned with the slide rails, preventing excessive lateral movement of the drive track while it longitudinally slides over the UHMWPE slide strip of the slide rails.
However, although the drive track remains in contact with the slide rails along much of the length thereof, there is typically a gap between the drive track and the slide rails near the forward upwardly curved portions of the slide rails, between the front drive axle and the forward end of the slide rails. This front portion of the drive track is accordingly unsupported by the slide rails. During operation of the snowmobile, especially over uneven terrain, this unsupported front portion of the track tends to buckle inwardly and outwardly due to the changing tension in the track or the result of uneven terrain. This rapid buckling of the track can result in contact between the steel clips on the track and front edges of the slide rails. This contact makes an undesirable noise and causes vibrations which are transferred to the driver and passengers of the snowmobile.
Some attempts have been made to address this problem. Particularly, the number of steel clips on the inside of the drive track have been reduced, by locating such clips only between every second or third hole for example, in an attempt to reduce the amount of noise created by their contact with the UHMWPE slide strips of the slide rails. However, proper alignment of the drive track cannot be maintained if too many steel guide clips are removed from the track.
Therefore, there remains a need to reduce the noise and vibrations cause by the contact between the drive track and the slide rails of a snowmobile, without negatively affecting the alignment of the drive track on the slide rails.